A Deep Dive into Native Lazy-Loading for Images and Frames
CSS - Tricks
MAY 15, 2019
You might have to perform a hard reload ( CTRL + Shift + R ) to re-trigger range requests. Make sure your servers support the HTTP Range: 0-2047 header and respond with status code 206 (Partial Content) to prevent them from delivering the full image twice. If this column is filled, the browser made a successful range request.
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